One third to one half of psychiatrically hospitalized youth is readmitted, with highest readmission risk 15-30 days post discharge and more than 80% readmitted within three months. The proposed study involves in vivo characterization of naturalistic phenomena associated with suicide risk after discharge adolescents using ecological methods and devices that allow acoustic capture of an individual's social environment and self-reports of experienced affect. We propose that social context and experienced affect are reciprocally reinforcing and that a reactive style involving close coupling of stressful social context (isolation, conflictual or high affect interactions) with affect reactivity (rapidly changig, intense affect, with slow return to baseline) increases risk for suicidal thoughts and behaviors. We also examine childhood maltreatment and epigenetic markers as predictors of post-discharge reactivity. Two hundred youth hospitalized for suicidal thoughts and behaviors will be followed prospectively using ecological methods and devices for three weeks following psychiatric discharge; suicidal thoughts and behaviors will be reassessed at 6 months. The present study further innovates through the incorporation of affect reactivity biomarkers (in-hospital blood samples for assessment of DNA/DNAm/expression). The proposed study merges multiple fields of study and permits an innovative and thorough characterization of the real-world interplay of affect and social context. Results of this investigation will inform a number of intervention approaches including family therapy, EMA-based adjunctive intervention, and pharmacological approaches.